Over the last year I have developed a mercury pot design to be available commercially and images of it can be seen in the updated gallery for mercury pots by CasedImage.com.
It took 4 prototypes and a lot of effort to get on top of the issues of electrical heat engineering and the thermodynamics of a large steel pot with a small amount of mercury in it. It did jump in at the deep end in designing it to take a maximum format of 8×10 inches, but I wanted a piece of professional equipment that would sustain some of the large of amount of investment required. It allows space for two half plates to be developed at the same time as well as catering for whole plate, which was my own personal preference also. It has a electrical heating system that has a digital controller which uses logarithms to manage a stable temperature. Despite this, another main feature that I sort in the design is that it has a telescoping stand (while keeping the overall footprint very compact) for use with heating by alcohol lamp. Most would use the electrical heating option but I wanted the pot to be able to be used in those rare occasions, in the outdoors/where there is no electrical supply. For those occasions it has a battery powered temperature display, which uses the same temperate sensor as the electrical heat system. It has a double darklside/airlock entry to the interior, made of stainless steel stopped slides and cnc machined Ultra High Molecular Weight Polyethylene (UHMWPE). It also has clear acrylic walls to impede the airflow in a fume hood from cooling the heat elements and making their task more difficult.